Application Research Of On-site Occult Blood Trace Discovery Recorder

As a common biological evidence,occult blood traces plays a vital role for detecting cases.Common show of occult blood traces include physical method,chemical method,optical test method,etc.However,these show methods have problems such as easy destruction of the sample and complicated operation,and it is impossible to show blood traces quickly and efficiently at the crime scene.Therefore,it is of great significance to study high-integration and convenient non-destructive testing devices,and to show occult blood traces efficiently and without loss.This paper applies the new equipment on-site occult blood trace discovery recorder developed by iridescent model(Beijing)Technology company.in order to achieve the purpose of high-efficiency,non-destructive extraction of occult blood.The instrument has the advantages of high integration,high convenience.It is divided into two kinds of different color light source of occult blood trace discovery recorders,one is red light source HC-EVFR-IRD equipment,and the other is green light source HC-EVFR-BLD device.The thesis is completed: 1.Showing and discrimining the occult blood traces and the special film fake blood by the device on the five common test objects of cloth(cotton,hemp,polyester),wooden floor,wallpaper,paint wood and kraft paper 2.Studying the depth of the background color on each object affects the appearance of occult blood traces and distinguishes the special effects of fake blood;3.Changing the spot occult blood traces to find the effect of the different color light sources of the recorder on the display of occult blood traces and the identification of special effects of fake blood.Adjust the camera parameter values,get the experimental results,summarize the use rules of the instrument,and hope to promote the modern development of the non-destructive testing device.The experimental research shows that: 1.Using the occult blood traces device reveals the occult blood traces and discrimins the false blood.The effect is better and the inspection efficiency is high;2.Among the five kinds of inspection objects,blood trace and a false blood trace on the object whether it is a dark color or a light color,the spot occult blood trace trace recorder can have a good appearance and discrimination effect,and is not subject to color depth limit;3.Extracting the occult blood traces on the object and selecting the HC-EVFR-BLD device for the green light source of the recorder to select the occult blood traces for the extraction;4.Identifying the occult blood traces and the special film fake blood,using the spot occult blood trace to find the recorder red light source HC-EVFR-IRD device.The innovation of this thesis: 1.The paper uses a new type of highly integrated,fast and convenient on-site occult blood trace discovery recorder,which is currently not used in China;2.This experiment breaks through the naked eye evaluation standard for the experimental display effect.By calculating the image variance value of the same region in the experimental image,the contrast effect of the experimental image is analyzed according to the magnitude of the variance value,and the purpose of quantifying the experimental effect map is achieved.